My '09 Subaru legacy has 62,000 on it. It's been running fine all these years. recently, my temperature gauge needle is slowly rising. Not going completely into the red but just under it. No smoke or steam coming from my engine. Happened a few times last week - once after running for 15 minutes on the highway another for running for over an hour. It does not happen regularly - it's very random. Got my radiator flushed, new thermostat, checked the hoses, checked the head gasket. Anything that could cause it to overheat is fixed. I'm thinking it's something non-engine related due to non-smoking or steaming. No engine lights go on. Just temperature gauge raising just under the red. Help! Please anybody have this problem? I'll appreciate the help.